Method and apparatus for building a tobacco stream



Jan. 27, 1970 J. GGMA NN 3,491,769

METHOD AND APPARATUS FOR BUILDING A TOBACCO STREAM I Filed Oct.' 19. 1966 F y] I; 512 302 5.94 539 5.96 o n o O O O 0 q q o o o o o o c 0 0 0 0 o o 0 0 0 030 0 0 0 03 Jas INVENTOR.

United States Patent ice Int. Cl. A24c 5/39 US. Cl. 131-84 9 Claims ABSTRACT OF THE DISCLOSURE A continuous tobacco stream is formed by feeding a continuous shower of tobacco particles against a perforated belt travelling longitudinally in a stream building zone whereby the belt entrains the particles and such particles form a growing tobacco stream each successive increment of which contains more tobacco than the preceding increment. The growing stream is confined laterally so that its width increases in the direction of travel of the belt and the particles of the growing stream are held against movement with reference to the belt by suctron in such a way that the rate of air flow through successive increments of the growing tobacco stream is maintained at a constant value.

This application is a continuation-in-part of my co pending application Ser. No. 554,505, filed June 1, 1966.

The present invention relates to a method and apparatus for building a tobacco stream. More particularly, the invention relates to a method and apparatus for building a continuous tobacco stream of uniform density which can be converted into a filler for cigarettes or like rod-shaped tobacco-containing products.

In presently known apparatus used to build a contmuous tobacco stream, particles of tobacco are showered or propelled against a travelling conveyor belt which constitutes the bottom wall of a channel. The width of the channel is constant and its side walls are stationary. Therefore, particles of tobacco adjacent to such fixed side walls are subjected to an undesirable braking or retarding action which leads to accumulations and results in the formation of a non-uniform stream, Attempts to avoid such frictional engagement between moving tobacco particles and fixed side walls of a stream building channel include the utilization of a longitudinally and transversely flexible belt which is guided in a trough so that its marginal portions constitute the side walls of the tobacco-receiving channel. A serious drawback of such constructions is that a belt which is flexed transversely can stand very little wear and must be replaced at frequent intervals whereby each such replacement necessitates complete shutdown of the stream building apparatus and of the machine which receives the stream.

Other known attempts to prevent localized accumulations of tobacco particles in the stream building zone include the utilization of a suction chamber which draws a current of air across the developing tobacco stream and overcomes friction between stationary side walls and such tobacco particles which are in contact with the side walls. This solution is satisfactory only if the air current is very strong so that it can fully overcome friction between stationary side Walls and adjoining tobacco particles; however, an overly strong air current is likely to expel from tobacco too much moisture, together with certain aromatic substances, which affects the quality of the ultimate product.

3,491,769 Patented Jan. 27, 1970 Accordingly, it is an important object of the present invention to provide a novel and improved method of building a continuous tobacco stream in an apparatus wherein the stream is built up in a channel having stationary side walls and a travelling flat bottom wall, and according to which the braking action of stationary side walls upon the adjoining particles of the developing stream is overcome in a very simple and unobvious way.

Another object of the invention is to provide a method of the just outlined characteristics according to which the stream of tobacco particles is built up in such a way that each successive increment of the fully grown stream contains the same or substantially the same amount of tobacco.

A further object of the invention is to provide a method of building up a tobacco stream with minimal drying of tobacco particles and by expulsion of minimal amounts of valuable aromatic substances.

Still another object of the invention is to provide an apparatus wherein the stream of tobacco particles is built up in such a way that its uniformity depends mainly on the rate at which the particles are being fed into its channel and wherein the particles of the growing stream are effectively held against movement with reference to each other.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved stream building apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic side elevational view of a cigarette making machine embodying a stream building apparatus which is constucted in accordance with the present invention, a portion of the channel which defines the stream building zone being broken away;

FIG. 2 is a transverse vertical section through the stream building apparatus as seen in the direction of arrows from the line IIII of FIG. 1;

FIG. 3 is a horizontal section as seen in the direction of arrows from the line IIIIII of FIG. 2;

FIG. 4 is a diagram illustrating the relationship between the length and width of the channel;

FIG. 5 is a diagram showing the relationship between the length of the channel and the resistance offered to the flow of an air current across successive increments of the growing tobacco stream; and

FIG. 6 is a section similar to that of FIG. 3 but showing a portion of a different stream building apparatus.

Referring first to FIG. 1, there is shown a stream building apparatus which is embodied in a cigarette making machine. The latter comprises a distributor 304 which forms part of the stream building apparatus and is disposed above an elongated stream building zone A defined by a portion of an elongated channel 306 also forming part of the stream building apparatus. This apparatus further comprises an endless formanous conveyor belt 324 which is trained around rollers 328 and is driven by a roller 326. Further rollers 330 are provided to subject the belt 324 to requisite tension.

The cigarette making machine further comprises a second conveyor here shown as a suction wheel 308 having a circumferential groove 1308 which receives from the belt 324a fully grown tobacco stream 401 and advances such stream past a trimming device 301 and on toward an endless transfer belt 310 cooperating with a mechanical stripping member 303 to remove the equalized stream from the groove 1308 and to direct it onto the upper stringer of an endless conveyor belt 309 forming part of a conventional wrapping mechanism 302. This wrapping mechanism provides the equalized stream with a wrapper of cigarette paper tape 311 and advances the resulting wrapped cigarette rod 312 past a cutting device 305 which subdivides the rod 312 into a series of successive cigarettes 313 of unit length or multiple unit length. Such cigarettes are then fed into the axially parallel peripheral grooves of a driven drumshaped conveyor 307 serving to advance the cigarettes to a filter cigarette machine or to another destination.

The distributor 304 comprises an endless feed belt 370 which is shown in FIG. 2 and is trained around a driven roller 372. The upper stringer of the belt 370 feeds a continuous carpet or fleece 380 of tobacco particles which are showered into an upwardly diverging chute 360. As shown in FIG. 2, the chute 360 receives a shower of discrete tobacco particles and such shower is formed along the full length of the stream building Zone A,

namely, from a left-hand end wall 394 and all the way to a right-hand end wall 396 of the chute. Thus, the width of the feed belt 370 at least approximates the length of the zone A. The upper end of the chute 360 is partially closed by an arcuate bafile 361 which defines with one side wall 356 of the chute an elongated orifice or slot 359 for admission of air. Additional air can enter the chute 360 along the upper stringer of the belt 370 and along the concave underside of the bafile 361. The manner in which the carpet 380 is formed on the belt 370 is well known from the art of conventional tobacco distributors and forms no part of the present invention. This carpet is of constant width and height so that each of its increments contains the same or nearly the same amount of tobacco particles.

The side walls 356, 358 of the chute 360 diverge upwardly toward the discharge end of the feed belt 370, but their lower marginal portions 362, 363 are located in vertical planes which diverge in a direction from the left to the right, as viewed in FIG. 3, namely, in the direction of travel of the upper stringer of the belt 324 which intercepts the descending tobacco particles and advances them lengthwise of the zone A and into a steam conveying or advancing zone B. The marginal portions 362, 363 of the side walls 356, 358 constitute the side walls of the aforementioned channel 306. This channel futher comprises a bottom wall or base 338 having a plate-like rigid apertured central portion 339 which constitutes a backing member for the upper stringer of the belt 324 and is formed with perforations or apertures 386 of identical cross-sectional area. The backing member 339 supports the upper stringer of the belt 324 from below so that the upper surface of this belt lies flat in a horizontal plane. The width of the tobacco-receiving space 322 above the upper stringer of the belt 324 increases in a direction from the end wall 394 toward the end wall 396, and the width of the belt 324 is such thatit intercepts all descending tobacco particles, regardless of the Width of the space 322. As shown in FIG. 2, the backing member 339 is formed with a shallow recess 342 which receives the upper stringer of the belt 324 so that the top surface of the belt lies flush with the top surface of the base plate 338. Suitable backup beams 340, 341 are fixed to the base plate 338 to support the marginal portions 362, 363 of the side walls 356, 358 and to prevent uncontrolled inflow of air into the space 322.

The end wall 394 extends downwardly and close to the upper stringer of the belt 324. The end wall 396 is spaced vertically from the upper stringer of the belt 324 so that it cannot interfere with travel of the fully grown t9 2a99 str am 401 into the st eam ash eas n on B.

The belt 324 is foraminous but its apertures are too small to permit passage of tobacco particles. The permeability of each successive increment of the belt 324 is the same so that, in the absence of diverging marginal portions 362, 363, and in the absence of the backing member 339, each increment of this belt would permit the same amount of air to flow therethrough. For example, the belt 324 may consist of silk threads or it may be made of perforated steel band stock.

The lower ends of apertures 386 in the backing member 339 communicate with a suction chamber 332 which forms part of pneumatic means for establishing a pressure differential between the upper side of the belt 324 (space 322) and the underside of the member 339. The suction chamber 332 extends lengthwise below the zones A, B and is connected with the intake of a suction fan 336 by a suction pipe 334. The housing 378 of the suction chamber 332 is afiixed to the base plate 338.

The aforementioned tobacco-receiving space 322 is open at its upper side but is otherwise sealed against entry of air because the end wall 394 extends close to the upper stringer of the belt 324. The space between the lower edge of the end wall 396 and the upper stringer of the belt 324 is normally sealed by the fully grown tobacco stream 401 which is advanced toward the groove 1308 of the suction wheel 308. The underside of the space 322 is closed by the belt 324 and its lateral sides are closed by the marginal portions 362, 363 of the side walls 356, 358. The suction chamber 332 insures that no air will penetrate into the space 322 from below. The divergence of marginal portions 362, 363 need not be very pronounced but is continuous all the way from the end wall 394 to end wall 396. In accordance with a feature of my invention, the marginal portions 362, 363 preferably resemble flat panels or walls which extend all the way to the downstream end of the zone B and are provided with smooth internal surfaces to offer little resistance to forward movement of the tobacco stream. Thus, the width of the space 322 between the side walls 362, 363 increases all the way to the righthand end of the suction chamber 332 where a transfer zone C begins.

In operation, the personnel in charge will start the motor which drives the rollers 326 and 372 so that the feed belt 370 begins to deliver a continuous shower of discrete tobacco particles which are intercepted by and thereupon advance with the exposed upper surface of the belt 324 in the recess 342. The personnel in charge will also start the motor for the fan 336 and the main drive which rotates the suction wheel 308 and imparts motion to the trimming device 301, transfer belt 310, belt 309, conveyor 307, cutting device 305 and the device (not shown) which supplies the tape 311.

The leading end of the carpet 380 on the feed belt 370 is converted into a shower which descends through the chute 360 and forms on the upper stringer of the belt 324 a growing wedge-like tobacco stream 400 each successive increment of which contains more tobacco than the preceding increment. The width of this growing stream 400 in the space 322 increases in a direction toward the end wall 396 because the marginal portions 362, 363 of the side walls 356, 358 diverge in a direction toward and along the advancing zone B. This latter zone receives a fully grown tobacco stream 401 which is fed into the transfer zone C to be sucked up into the groove 1308 of the suction wheel 308 for travel to the trimming device 301 and onto the belt 309 in a manner well known from the art of cigarette making machines. The growing stream 400 is held against the upper surface of the belt 324 by suction produced by the fan 336 which latter causes a current of air to flow downwardly through the space 322, through the pores of the belt 324, through the exposed orifices 386 of the backing member 339, and into the suction chamber 332. Since the m rginal portions 362, 363 of the i l f Walla 35 6, 358 continue to diverge along the full length of the advancing zone B, they ofier no appreciable resistance to the movement of particles which form the fully grown stream 401. The same holds true for the stream building zone A wherein the marginal portions 362, 363 diverge all the way between the end walls 394, 396. The current of air induced by the suction chamber 332 compels the particles showered by the belt 370 to travel with the upper stringer of the belt 324, i.e., such current prevents relative movement between the particles which form the stream 400 and the belt 324 as well as relative movement between successively deposited particles of the stream 400.

As stated before, the cross-sectional area of each aperture 386 in the backing member 339 of the base plate 338 is the same. Also, each unit area of the backing member 339 contains the same number of apertures 386 so that each such unit area ofiers the same resistance to the flow of air therethrough. The permeability of each unit area of the belt 324 is also the same so that each region of this belt offers the same resistance to the flow of air. However, and since the width of the space 322 increases in a direction toward the transfer zone C, the permeability of each successive increment of the exposed portion of the belt 324 in the recess 342 increases in the same direction. This is advisable because, otherwise, air drawn into the suction chamber 332 would seek to find the path of least resistance and would pass from the space 322 through the belt 324 and backing member 339 in immediate proximity of the end wall 394 where the height of the growing tobacco stream 400 is minimal. By utilizing a belt and a backing member whose permeability is constant in each unit area, I insure that the resistance to the flow of air through the growing tobacco stream 400 is the same all the way between the ends of the zone A so that each freshly deposited particle is held with the same force and immediately shares lengthwise movement of the belt 324. The relationship between the resistance to flow of air through successive increments of the exposed portion of the belt 324 in the space 322 and the divergence of the marginal portions 362, 363 is preferably such that the resistance to flow of air :from the space 322 into the suction chamber 332 is the same along the full length of the zone A, provided of course that the belt 370 feeds tobacco particles at a reasonably uniform rate all the way from the end wall 394 to the end wall 396, and provided that the magnitude of the angle of divergence of the marginal portions 362 and 363 is properly selected to provide the desired result. The fan 336 is preferably adjusted in such a way that the force exerted by the air current against the exposed tobacco particles in the space 322 is just sufficient to prevent relative movement between such exposed particles and the particles therebelow. This insures that the current of air flowing across the channel 306 does not expel excessive amounts of moisture or aromatic substances.

In the zone B, the rate of air flow through the belt 324 increases because the space 322 widens but the amount of tobacco in each successive linear increment of the fully grown stream 401 is the same. Air flowing across the zone B prevents undesirable shifting of particles in the fully grown stream 401 with reference to each other. Such shifting could be caused by contact with the marginal portions 362, 363 and/or by the action of atmospheric air above the exposed top surface of the stream 401.

By suitable selection of apertures 386, and by provision of suitable controls in the suction chamber 332, the flow of air along the full length of the space 322 can be regulated in such a way that the current of air will have an optimum effect upon the growing stream 400.

It is also within the purview of my invention to replace the suction chamber 332 and fan 336 with a blower which blows a current of air into the space 332 from above.

FIG. 6 illustrates a portion of a modified stream building apparatus wherein the backing member 539 is formed with apertures 586 whose diameters increase in the direction of tobacco travel. Thus, the resistance offered by unit areas of the backing member 539 to the flow of air across the stream building zone A decreases from the end wall 594 toward the end wall 596. Such a backing member can insure that the effect of suction upon each successive increment of the growing tobacco stream is the same and that the density is constant throughout the growing stream. It is not always necessary to provide the backing member 539 with identically dimensioned apertures; for example, the two outer rows of apertures 586 shown in FIG. 6 could have identical diameters along the full length of the backing member 539 but the diameters of apertures in the median row then increase in a direction away from the end wall 594. In the zone B, each unit area of the backing member 539 offers the same resistance to flow of air into the suction chamber therebelow.

The backing member 539 of FIG. 6 will be used if the provision of divergent side walls 562, 563 does not suffice, by itself, to insure a desirable reduction in resistance offered by successive increments of the member 539 to flow of air from the space above the belt 524 into the suction chamber below the backing member 539. Thus, a satisfactory reduction in such resistance can be achieved either by making the marginal portions 362, 363 or 562, 563 divergent or by making the marginal portion divergent and by utilizing a backing member 539 wherein the resistance oifered to flow of air by unit areas in successive increments of the backing member decreases in the direction of tobacco travel.

If the unit areas of the backing member 539 of FIG. 6 oiTer a gradually decreasing resistance to the flow of air in the zone A and also in the zone B, and if it is desired that the resistance to flow of air in each successive increment of this backing member along the zone B should remain constant, the suction chamber below the backing member 539 will accommodate suitable baffles or other obstructions which are disposed below the zone B and compensate for decreasing resistance of successive increments between the zone A and zone C.

The diagram of FIG. 4 illustrates the relationship between the length l and the width b of the zones A and B in various embodiments of my apparatus. The diagram of FIG. 5 shows the relationship between the length l and the resistance s offered to the flow of air by unit areas of the backing member 339 or 539. In considering FIG. 5, one should bear in mind that the resistance s of successive unit increments of the backing member decreases if the width of the space above the backing member increases and if the resistance of each unit area of the backing member is the same.

The curve 451 of FIG. 4 is a straight line which is inclined with reference to the abscissa. The curve 452 of FIG. 5 is parallel to the abscissa. Each of these curves is indicative of conditions prevailing in the apparatus of FIGS. 1 to 3 wherein the width of the space 322 increases gradually from the end wall 394 all the way to the zone C and wherein each unit area of the backing member 339 offers the same resistance to flow of air therethrough.

The curve 453 of FIG. 4 parallels the curve 451 along the stream building zone A but runs horizontally in the zone B to indicate that the width of the space 322 in the zone B is constant. The strongly pronounced transition between the two mutually inclined portions of the curve 453 indicates that parts of marginal portions 362, 363 bounding the space 322 make a pronounced obtuse angle in the region where the zone A ends. The curve 454 of FIG. 4 indicates that the transition between the mutually inclined parts of the marginal portions 362, 363 is gradual.

The curve 455 of FIG. 5 indicates the resistance s of the backing member 539 shown in FIG. 6. This curve 455 slopes toward the abscissa in the zone A because the resistance s of unit areas in successive increments of the backing member 539 decreases in the direction of tobacco travel. In the zone B, each unit area of the backing member 539 offers the same resistance to flow of air; therefore, the second half of the curve 455 coincides with the curve 452. The apparatus of FIG. 6 can compensate for increases in the height of the growing stream which are more pronounced than in the apparatus of FIGS. 1 to 3. I The ratio lzb and/or the ratio l:s depends on the desired height of the tobacco stream in zone B and on certain other factors. It is preferred to select the pressure differential in such a way that the particles in the topmost stratum of the growing tobacco stream are subjected to a pressure which is just sufficient to prevent them from moving relative to the particles therebelow.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairlyconstitute essential characteristics of the generic and specific aspects of my contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is:

1. A method of building a continuous tobacco stream in an elongated stream building zone, comprising the steps of feeding a continuous shower of tobacco particles against a surface travelling longitudinally of said stream 'building zone so that such particles are entrained by and form on said surface a growing tobacco stream each successive increment of which contains more tobacco than the preceding increment; laterally confining the growing stream so that its width increases in the direction of travel of said surface; and establishing a substantially uniform pressure differential at the opposite sides of said surface along the length of said zone to induce the flow of an air current through such surface and in a direction to hold the growing tobacco stream against said surface.

2. A method as set forth in claim 1, further comprising the step of maintaining the rate of air flow through each successive linear increment of the growing tobacco stream at a constant value.

3. A method as set forth in claim 2, further comprising the step of conveying the fully grown tobacco stream beyond said stream building zone and continuously maintaining the rate of air flow through each successive linear increment of the fully grown tobacco stream at said constant value.

4. Apparatus for building a tobacco stream, comprising a channel defining an elongated stream building zone and having side walls diverging in a predetermined direction from one end toward the other end of said zone; an endless conveyor having a portion arranged to travel in said channel between said side walls in said predetermined direction; a feed for showering tobacco particles into said channel and against said conveyor portion whereby the particles are entrained by and form on said conveyor a growing tobacco stream each successive increment f which contains more tobacco than the preceding increment; said conveyor being forarninous and said channel comprising air permeable backing means adjacent to said conveyor portion, and further comprising pneumatic means for establishing a pressure differential across said conveyor portion and said backing means to induce the flow of air in a direction to urge the growing tobacco stream against said conveyor.

5. Apparatus as set forth in claim 4, wherein said pneumatic means. comprises a suction chamber adjacent to said backing means opposite said conveyor portion.

6. Apparatus as set forth in claim 4, wherein the permeability of each successive linear increment of said backing means is the same, as viewed in said predetermined direction.

7. Apparatus as set forth in claim 4, wherein the permeability of each successive linear increment of said backing means and said conveyor is respectively the same so that, in the absence of tobacco in said zone, the resistance of successive linear increments of said backing means and said conveyor portion to the flow of air across said conveyor portion and between said side walls decreases in said predetermined direction and wherein said channel extends beyond said stream building zone and the permeability of each successive linear increment of said backing means is constant in the region beyond said stream building zone.

8. Apparatus as set forth in claim 4, wherein the permeability of each successive linear increment of said backing means and said conveyor is respectively the same so that, in the absence of tobacco in said zone, the resistance of successive linear increments of said backing means and said conveyor portion to the flow of air across said conveyor portion and between said side walls decreases in said predetermined direction; and wherein said backing means is provided with apertures of identical cross-sectional area and wherein the number of such apertures per unit area of said backing means is constant.

9. Apparatus as set forth in claim 4, wherein said backing means is provided with apertures and wherein the combined cross-sectional area of such apertures in successive unit areas of said backing means increases in said predetermined direction along said stream building zone.

References Cited UNITED STATES PATENTS JOSEPH S. REICH, Primary Examiner U.S. Cl. X.R. 131-1 10 

